1. Field of the Invention
The present invention relates to a surface acoustic wave device and a method of adjusting an LC component thereof, especially a surface acoustic wave device mounted on a base substrate by a stud bump and a method of adjusting an LC component thereof.
2. Description of the Related Art
A conventional surface acoustic wave (SAW) device is disclosed in, for example, Japanese Patent Application Kokai Number 2000-114916 (pages 4-5 and FIGS. 1-2). In the conventional SAW device, an SAW chip containing an inter-digital transducer (IDT) is mounted on a base substrate by the flip chip mounting method. Each of electrode pads has a top end which is provided with a bump and disposed in the center of the SAW chip. Since the bump is disposed in the vicinity of the center of the SAW chip, the stress produced by the difference in the coefficient of thermal expansion between the SAW chip and the base substrate is reduced, thus preventing wiring defective caused by heat.
In an SAW device, the characteristics of individual device are often not uniform if the thickness and shape of the IDT and the electrode pad are uneven. When the SAW device is used under high operational frequency, the influence of the uneven thickness and shape is large. Especially, in an SAW filter, such as an SAW duplexer, it is required that an LC component of the individual SAW device is adjusted to achieve a predetermined resonant frequency. However, in the SAW device disclosed in Japanese Patent Application Number 2000-114916, the position of the bump is limited to a specific area of the device so that the degree of freedom of the bump position is not large and it is difficult to adjust the LC component of the individual SAW device and also the LC component at a specific position in the SAW device.